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引用次数: 0
摘要
线性化是网络理论中最重要的课题之一。可线性化网的一个特殊类别是格拉斯曼可线性化网。阿基维斯给出了这类网的特征,表明格拉斯曼可线性化网等同于等轴网和横向大地网。阿基维斯给出的等轴测地网和横轴测地网的障碍是局部计算的,很难将它们解释为与网相关的唯一切尔连线的扭转或曲率。在本文中,我们利用纳吉的网形式主义、与向量微分形式相关的弗洛勃-内延胡伊理论(Frölisher-Nejenhuis theory for derivation associated with vector differential forms)和切线束上张量代数的格里方连接理论(Grifone's connection theory for tensorial algebra on the tangent bundle),找到了用扭转、曲率和纳吉张量表示的与近格拉斯曼结构相关的不变式,并用这些不变式为等轴网、横向测地网、可格拉斯曼化网和可平行化网提供了解释。
Characterization of Isoclinic, Transversally Geodesic and Grassmannizable Webs
One of the most relevant topics in web theory is linearization. A particular class of linearizable webs is the Grassmannizable web. Akivis gave a characterization of such a web, showing that Grassmannizable webs are equivalent to isoclinic and transversally geodesic webs. The obstructions given by Akivis that characterize isoclinic and transversally geodesic webs are computed locally, and it is difficult to give them an interpretation in relation to torsion or curvature of the unique Chern connection associated with a web. In this paper, using Nagy’s web formalism, Frölisher—Nejenhuis theory for derivation associated with vector differential forms, and Grifone’s connection theory for tensorial algebra on the tangent bundle, we find invariants associated with almost-Grassmann structures expressed in terms of torsion, curvature, and Nagy’s tensors, and we provide an interpretation in terms of these invariants for the isoclinic, transversally geodesic, Grassmannizable, and parallelizable webs.
期刊介绍:
Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance.
Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.